Telecommunication switching system



OC. 29, 1946. G, DEAKlN TELECOMMUNICATION SWITCHING SYSTEM 4 sheds-sheet 1 Filed April 2l, 1944V @GEES uwbw mkg oct. 29, 1946. G DEAKIN l TELECOMMUNICATION- SWITCHING SYSTEM Filed April 21, 1944 Oct. 29, 1946. G DEAKIN TELEQOMMUNICATION SWITCHING SYSTEM Filed-April 2l, 1944 4- Sheets-Sheet 3 AGENT.

Oct. 29, 1946. G. Dl-:AKIN 2,410,050

` TELECOMMUNICATION SWITGHING SYSTEM Filed April 2l, 1944 4 Sheets-Sheet 4 MAQ Patented Oct. Z9, 15946 TELECOMMUNICATION SWITCHING SYSTEM Gerald Deakin, New York, N. Y., assigner to Interd 4national `Standard yElectric Corporation, New York, N. Y., a corporation of Delaware Application April 21, 1944, Serial N0. 532,143

20 Claims. 1

This invention relates to new and useful improvements in switching systems and, more particularly, to systems of the type 'disclosed in my copending application, Serial No. 532,142, `filed April 21, 1944.

The object of the present invention is to simplify the switching system `in which a set of ten keys are used for controlling a plurality of successive selecting operations,

` In said application a key-sending system is disclosed in which six tube `circuits are connected permanently in the register, each to a separate potential. VSuch register recordingA circuit is almost instantaneous in operation.

In accordance with the` present invention a set of ten keys controls a single tube circuit in a register. This circuit, when operated, applies a series of ten potentials tothe grid of a triode in rapid succession, and causes it to operate when the proper potential is reached. The return to normal of the depressed keys is controlled by a governor, and the speed of operation is limited to about four digits per second. The arrangement is particularly useful for P. A. B. Xs having short lines of about 300 ohms.

In the drawings, Fig. 1 is a circuit diagram ofv a substation equipped with a key set utilizing the features of the present invention;

Fig. 1a is a diagram by means of `which the theory of operation of the system willbe eluci dated;

Figs. 2-6a illustrate `the mechanical details of the key set; Fig. 2 being a cross section along lines 2-2 of Figy, Fig. 3 a cross section along lines 3 3 of Fig. 2, Fig. 4 an end View with parts broken away, Fig. 5 a detail of the contact actuating mechanism, Figs. 6 and 6a illustrating diagrammatically the contact arrangements controlled by keys 1-5 and 6 0, respectively, and

Fig. '7 shows as much of a register controller `as is necessary for an understanding of thepresent invention. i

Subscribers set circuit (Fig. 1)

First the electrical and then the mechanical details of the key set will be explained.

When any one of the buttons I to 5 is depressed, a resistor Rl to R5 is cut in on the return stroke of the key plunger which opens contact 2|. When any one of key buttons 6 to (l is depressed, the circuit is momentarily opened on the return of the plunger at contacts 26 and 2l. Shortly after the start of the return, contact 28 closes and cuts in resistor R6 to RIU, as the case may be. M

When any button is depressed, the home contact nest operates, first opening the receiver circuit at 22, then shorticircuiting the transmitter circuit at 23, and nally removing the shortcircuit from the key set at 24.

Key set assembly (Figs. Z-a) The key set assembly mounts in the subscriber's set. When any key button 25 is depressed, plunger 26 forces with its inclined surface 2l, a sliding bar 2S to the right, thus opening home contacts 22 and 23, as above-described. Part V29, attached to the plunger by rivet 30, engages friction wheel 3l, molded-or otherwise: attached' to a rotatable shaft 32, carrying. a `friction `disc33, rubbing. against spring `3.4. This` friction control serves no useful purpose on the downward stroke.

Shortly after Y.the home contacts operate, a pin 35 of thedepressed key engages the upper lip of a spring "35, forcing it still further against spring 3l. After the key is about three-quarters depressed, ,pin 35 engages the upper lip of spring 38, forcing this spring also against 3l. the plunger is all the way down, the pin 3,5 is free of the lower `lip of spring 33. It will thus be seen that when a key is depressed, only the home contact spring nest operates.

`When a keybutton is released, it is raised by coiled spring 39, and pin 35 engages first the lower lip of spring 38, forcing it away from spring 3l and breaking contact at 23. At the same time alug 4t on 38 (Fig. 3) forces spring 36 away from spring 3l, thereby breaking the contact 2| between springs 3l and `35, and thus momentarily opening the line circuit. When the plunger has returned `about one-fourth `of the distance,

pin 35 slips oi the upper lip of spring 38, which returns and makes contact with spring 3l, but spring` 36 is now engaged by pin 35, and contact 2l is held open to introduce the resistor in the circuit until the plunger commences to restore the home contact to normal.

'The double springs 33 and 33 are required `for keys 6 tou only (see Fig. 6a). `For buttons l to 5, only spring 36 is required (Fig. 6)

The speed of the return of the plungeriscontrolled by friction washer 33 and spring Stand the friction between 'rubber'wheel 3l and part 30. This simple form` of friction governor-may, of

course, be replaced by a more accurate'type of.

governor, such as the worm governor used inthe ordinary telephone dial. The system is :arranged to allow the operation of three keys per second.

When

Operation of register circuit (Fig. 7)

and immediately thereafter BR operates and o-pens the initial circuit. RBR applies high tension battery to the electrical discharge device comprising triodes V1 and 'V2 and gas valve GV, and closes the primary side of thedialing tone circuit, the secondary side of which is bridged across the calling line. AR operates slow releasingrelay RIR, which remains energized during the subsequent operation cf the register circuit.

The register circuit remains in this condition until the subscriber depresses a key button.

When a key button is depressed, no change in the register circuit takes place, but Ywhen the button is released, AR falls away due either to the momentary opening of the line circuit, in case any button R to RIO is operated, or to the high resistance of RI to R5, in case any one oi keys I to 5 is depressed. The value of the resistance which each key button cuts into the circuit on its return stroke is shown in Fig. la, as is the potential placed on the grid of V2 when any key is depressed.

rAssume now that button No. 3 is depressed. On'the return stroke AR falls away since key 3 introduces resistor R3, making the total loop resistance of the line 3300 ohms. AR is adjusted to fall oiwhen the loopresistance is increased ,tov approximately 1000 ohms.Y vWhen AR makes its back contact, it connects `the grid of V2 and resistor Rn to the b wire. In this particular case the potential of the b wire at this point is reduced to 30 volts (P3). At the same time, AR closes the starting circuit of a step-by-step operating device comprising a set of counting relays CR from ground, back GVR, front BR, back AR, 4

winding CRI to battery. A few milli-seconds after, CRI operates CRZ, thus placing the potential P normally on the back contact of CRS on the grid of Vl. The tube circuit now operates in the usual way, lights GV'which energizes GVR. The starting circuit is opened before CRS has time to operate.

',"When GVR makes its front contact, it energizes the corresponding XR relay, circuit from ground, front GVR, back AR, front CRI, front CR2, back CR3, back TRI, winding XR3 to battery. In parallel with this operation, GVR operates GSR. GSR operates AR and opens the high tension circuit, thereby releasing GVR and de-ionizing GV. AR locks up to the calling line and opens the operating circuit of XR3 which now locks upover a front contact in series with VTRI and front RCR. TRI operates and transfers the counting relay control to the next set of XR relays. AR opens the back contact circuit of GVR so that the counting relay circuit is not again energized when GVR makes its back contact.

All counting relays are made slightly slowreleasing so as to allow time for the energization of the XR relays. Resistor R2 to ground at the back contact of GVR is provided to reduce sparking when the common counting relay holding circuit is opened. It is not sucient to retain even one CR relay energized.

GSR is made slow enough to retain AR energized until the key plunger is restored to normal and the line circuit again closed.

F is a filter to prevent improper operation of the triodes by the dialing tone or the like.

When P. A. B. X stations are equipped for tenbutton local calling, out-trunk calls may be made in one of two ways, either by installing an ordinary dial on the subscribers set for those stations permitted to make/out-trunk calls, or by adapting the P. A. B. X register circuit to convert ten-button pulses into dial or other types of pulse required to operate the central oice equipment.v

A similar arrangement is disclosed in my copending application, Serial No. 533,466, led May 1, 1944, of which application, Serial No. 540,946, filed June 19, 1944, is a continuation, in which the keys are locked until the register responds and control the register by a combination of potential and polarity changes.

What I claim is: v

1. In a switching system, a controller having a plurality of operating positions, a source of current, a multi-electrode discharge device, means for establishing a connection between said controller and said device, a relay, means for operating said relay when potentials applied to two electrodes of said device bear a predetermined relationship to one-another, means including said connection for applying a different potential to one electrode in each position of the controller. means actuated by the controller for applying various potentials to the second electrode, and switching means variably operable under the control of said relay and the last-mentioned means.

2. The system accordingtovclaim 1, and means for operating the relay when the same potentials are applied to the two electrodes.

3. In a switching system, a controller having a pluralityl of operative positions, asource of current, a responsive device, means for applying a different potential to the responsive device in each position of the controller, step-by-step means for applying different potentials to the responsive device, means for operating the step-by-step means when the controller is actuated, a relay operated when thepotentials applied to the responsive device bear a predetermined relation to one-another, and switching devices variably oper able under the control of said relay and step-bystep means.V

4. The switching system according to claim 3, and means for operating the relay when the two potentials applied to the responsive device ar the same.

5. The switching system according to claim 3, and in which the step-by-step means comprises a set of counting relays having contacts for applying said potentials.

6. The switching system according to claim 3, and in which the controller is arranged toapply ten diierent potentials, and the stepby-step means comprises a set of nine counting relays, having contacts for applying said ten different potentials.

7. The switching system according to claim 3, and in which the controller comprises a plurality oi' keys and a corresponding number of resistances, one for producing each operating position', and means responsive to the association of any key for starting the step-bystep means to operate.

8. The switching system according to claim 3, and in which the controller comprises a plurality of keys and a corresponding number of resistances, one for producing each operating posi-S tion, and means responsive to the actuation of any key for starting the step-by-step means to apply one potential after the other;

.9. In a switching system, a controllerhaving a plurality of operating positions, a current source, a pair of triodes, means for establishing a connection Ybetween said controller and said-triodes, a relay, means for operating saidrelay `when the potentials applied to the grids of the two triodes bear a V.predetermined relationship to one-another, means ior applyingT a different potential to the grid of the rst triode in each `position of the controller, step-by-step means controlled by. said relay for applying different potentials to the grid of thesecond triode, means actuated by the controller for'starting the operation of the step-bystepmeans, and a plurality Aof digit storage devices variably operableunder the `control of'sai relay and step-'by-step means.

` 10.I In a switching system, a controller comprising a set oi keys, one for each operating .position of the controller, a current source, a pair of triodes, means for establishing'a connection between said controller and said triodes, a `resistance for each key switched into the connection when the key is operated, a relay, means for operating said relay when the Vsaine potentials are applied to the grids of the two triodes, means including said resistances for applying a different potential to the grid of the first triode in response to the operation of each key, step-by-step means controlled by said relay for applying said different potentials, one after the other, to the grid of the second triode, means actuated by the controller for starting the operation of the step-by-step means, and a plurality of storage devices variably operable under the control of said relay and stepby-step means.

11. In a switching system, a controller having a plurality of operating positions and operable in accordance with successive digits of a number, a D. C. source, a pair of triodes, a relay, means for operating said relay when the same potentials are applied to the grids of the two triodes, means for applying a different potential to the grid of the rst triode in each position of the controller, means including a set of counting relays controlled by said relay iorapplying said different potentials, one after the other, to the grid of the second triode, means actuated by the controller for starting the operation of the counting relays, and a storage device for each digit variably operable under the control of said relay and counting relays.

12. In a switching system, a normally inactive controller comprising a set of ten keys operable in accordance with a plurality of successive digits, a D. C. source, a pair of triodes, a two-wire circuit connecting the controller with the triodes, a relay, a gas valve for operating said relay when the same potentials are applied to the grids of the two triodes, a different resistance switched into the circuit by each key for applying ten different potentials to the grid of the first triode, means including a set of counting relays controlled by said relay for applying said ten different potentials, one after the other, to the grid of the second triode, means actuated by the actuated key for starting the operation of the counting relays, and a storage device for each digit variably operable under the control of said relay and counting relays.

13. The switching system according to claim 12, and in which nine counting relays have contacts for applying the ten diierent potentials.

14. In a switching system, a controller having ten operating positions and `comririsinga key Afor each position and movable `from a normal to an actuated lposition and returnto normal, a twowireline circuit, ten different resistances, one for each key, in series in thecircuit, a first contact for each key and a second contact 'for ve of the keys; the contacts of each keyfnormally short-circuit# ing the associated resistance, means controlled Vby eachA key for opening its nrst contact substantially throughout its return movement, means controlled by said iive keys for opening their second contacts `only during the beginning of the return movement, a4 device connected with the line circuit and comprising a iirst means responding once to the actuation of any key, a second means' variably operated dependent on the .key actuated; anda switching device jointly controlled bythe first and second means. Y

i 15. The switching system according to claim 14, and in which the first means comprises a relay actuated upon the opening of a contact by any relay.

16. The switching system according to claim 1li, and in which the nrst means comprises an electric discharge device having an electrode con-- nested with the circuit and responding onceV dur'- ing the return movement of each key.

1'7. The switching system according to claim 14, and in which the second means comprises a set of counting relays.

18. In a telephone switching system, a. receiver and a transmitter, a controller having ten operating positions and comprising a key for each position and movable from a normal down to an actuated position and return up to normal, means for governing `the speed at which said keys move, a two-wire line circuit, ten different resistances, one for each key, in series in the circuit, a first contact for each key and a second Contact for live of the keys, the contacts of reach key normally short-circuiting the associated resistance, a

home contact set, means operative upon the actu- Yation of any key and while any key is ofi-normal `iirst to open the circuit of the receiver,l then to short-circuit the transmitter, and then to remove a short circuit around all the keys, means controlled by each key for opening its rst contact substantially throughout its return movement, means controlled by said live keys for opening their second contacts only during the beginning of the return movement, a device connected with the line circuit `and comprising a rst means responding in the same manner in response to the actuation of any key, a second means variably operated dependent upon the key actuated, and a switching device jointly controlled by the first and second means.

19. In a telephone switching system, a controller having a plurality of operating positions and comprising a key for each position and movable from a normal to an actuated position and return to normal, a line circuit, a plurality of different resistances, one for each key, in series in the circuit, a rst contact for each key and a second contact for some of the keys, the contacts of each key normally short-circuiting the associated resistance, a contact set, means operative upon the actuation of any key and while any key is off-normal to remove `a, short-circuit around all the keys by operating the contact set, means controlled by each key for opening its first contact substantially throughout its return movement, means controlled by said some keys for opening their second contacts only during part of the return movement, a source of D. C. for the' line circuit, a responsive device connected with the line circuit and comprising a rst relay bridged across the line circuit and adaptedl to be rie-energized when the circuit is'opened in the two contacts of any of said some keys and also when connected in series with any one of the resistances associated with the other keys, an electric ldischarge device, a path closed to the device over a back contact of said relay from said circuit, a step-by-step means, a potentiometer across said source having a plurality of taps, contacts controlled byy the step-by-step means for connecting a diierent tap with the device, a starting circuit for Said step-by-step means controlled by said relay, a second relay operated when the same potentials are applied to the device, and an impulse storing device controlled by the second relay and the step-by-step means.

20. In a telephone switching system, a controller having ten operating positions and comprising a key for each position and movable from a normal down to an actuated position vand return upto normal, means for governing the speed at which said keys move, a two-wire line circuit, tendifferent resistances, one for each key, in series in the circuit, a first contact for each key anda second contact for ve of the keys, kthe contacts of each key normally short-circuiting the associated resistance, a contact set, means operative upon the actuation of any key and while any key is off-normal first to open in said contact set the short-circuit around all the keys,

means controlled by each key for opening its rst contact substantially throughout its return movement, means controlled by said ve keys for opening their second contacts only during the beginning of the return movement, a source of D.'C. for the line circuit, a responsive device connected with the line circuit and comprising a first relay operated when the circuit is opened in the two contacts of any of said ve keys and also when connected in series with any one of the resistances associated withthe other keys, an electric discharge device, a path controlled by said relay to said circuit from said device, other means controlled by said relay for applying different potentials one after the other to said device, a second relay operated when the potentials applied to the device bear a predetermined relationship to one-another, and a switching device controlled by the second relay.

GERALD DEAKIN. 

